Power driven hack saw



April 29 1941- P. MARSHALL 2,239,681

' POWER DRIVEN HACK SAW Filed not. 25, 19.39 2 sheets-sheet 1 Inventor fauZ Mari/MZZ.

April 29, 1941.v

P. MARSHALL POWER DRU/EN HACK SAW 2 Sheets-Sheet 2 Filed Oct. 25, 1939 .m M Z. Q@ d 7M Q N n y Q I/l//v//V/ M r M HL Z E U @M Dm, `Aid-wl*lfng- Erllmnlv mi l I QN A ftorneys Patented Apr. 29, 1941 UNITED STATES PATENT oEEicE POWER DRIVEN HACK SAW Paul Marshall, Dexter, N. Mex.

Application October 25, 1939, Serial No. 301,272

2 Claims.

This invention relates to a power driven hack saw, and has for the primary object the provision of a device of this character which may be easily and conveniently handled with the various parts thereof readily accessible for adjustment and repair and includes adjustable means for guiding the saw blade on its` non-cutting stroke and which acts to regulate the cutting depth of the blade and may be conveniently adjusted so that the blade may cut to various depths.

Another object of this invention is the provision of a power drive which elevates the blade in the cut made thereby during its non-cutting stroke with the blade guided during said stroke.

With these and other objects in view, the invention consists in certain novel features of construction, combination and arrangement of parts to be hereinafter more fully described and claimed.

For a complete understanding of my invention, reference is to be had to the following .description and accompanying drawings, in which Figure 1 is a side elevation illustrating a power driven hack saw constructed in accordance with my invention.

Figure 2 is a transverse sectional view taken on the line 2-2 of Figure 1.

Figure 3 is a transverse sectional View taken on the line 3-3 of Figure 1.

Figure 4 is a sectional view taken on the line 4 4 of Figure 1.

Figure, 5 is a vertical sectional view illustrating the device.

Referring in detail to the drawings, the numeral 5 indicates in entirety the frame of the hack saw and includes primarily end members 6 and 'l bothof which are of substantially framelike constructions including side plates connected by top and bottom plates all of integral construction. The end members 6 and 'I are joined by a tie member 8 so as to provide a rigid construction.

Arranged within lthe end members 6 and 'I are pairs of sprocket gears 9 over which are trained sprocket chains l equipped with suitable fastening means Il for detachably connecting thereto a hack saw blade I2. The rotation of the sprocket chains brings about reciprocation of the hack saw blade and one sprocket gear of each pair of sprocket gears has secured thereto bevel gears I3 which mesh with pinions I4 secured 0n the shafts I journaled within the end members and also are equipped with bevel gears I6 meshing with bevel gears Il secured on a drive shaft ,l B connected to the shaft oi an electric motor I9 in any well known manner. The electric motor I9 is mounted on one of the end members and is equipped with la handle 20 for .the handling and controlling of the device. It is to be understood that the electric motor may be readily connected to a -conventional electric output through an extension cord having a control switch.

Slidably mounted in grooves provided in the end members 6 and 1 are guide members 2l between which moves the hack saw blade while on its non-cutting stroke. 'Ihe guide members 2l being arranged in the grooves of the end members may be adjusted vertically and have secured thereto rack bars 22 engaged by gears 23 secured on a shaft 24. The shaft 24 is journaled in bearings 25 carried by the end members and is equipped with a finger piece 26 so that the shaft may be rotated in opposite directions for the purpose of raising Iand lowering the guide members 2| in the grooves of the end members 6 and l. The guide members act to guide the movement of the saw blade on its non-cutting stroke and also act as means for limiting the cutting action of the blade as to depth in the work. In use, the operator grips the device by the handle 20 with one hand and the :linger piece 26 of the shaft 24 by .the fingers of the other hand, whereby the shaft 24 may be held against accidental rotation. When starting a cut in a piece of work, the finger piece 26 is rotated to lower the members 2| until the teeth of the blade project slightly below said members 2| when the blade is on its cutting stroke. With the motor I9 in operation the teeth of the blade are brought into engagement with the work between the end members 6 and 1. After the blade has started to cut the work, the members 2|' come in contact with the work and the operator rotates the finger piece 26 in ya reverse direction to permit the blade to progress in its cutting action on the work, it being understood inorder for the cutting of the work to progress, the linger piece 26 must be gradually rotated in the latternamed direction in order for the blade to ad- Vance into the work.

Whenever the operator stops rotating the finger piece 26, the members 2| being in engagement with the work then Iact to limit the cutting depth of the blade into the work.I v

It is believed that the foregoing description, when taken in connection with the drawings will fully set forth the construction and advantages of this invention to those skilled in the art to which such device relates, `so that further de tailed description will not be required.

and for limiting the cutting action of said blade in Work and means for adjusting said guide means with respect to the saw blade and the work acted on by said blade.

2. A hack saw comprising frame members, a tie means between said frame members, endless sprocket chains mounted in said frame members, a hack saw blade lconnected to said endless sprocket chains, an electric motor connected to one of said frame members, a drive means connecting said motor to said endless sprocket chains, spaced guide members slidably supported on the frame construction, for controlling the cutting action of the blade in work, rack bars secured to said guide members an operating shaft carried bythe frame members for rotation in opposite directions, gearing connecting said shaft to the rack bars.

PAUL MARSHALL. 

